This invention pertains to flow detectors and, more particularly, to orifice plates for measuring fluid flow.
Pipelines are used to convey numerous types of fluids such as natural gas (methane) and other light hydrocarbon gases, steam, hydrogen sulfide, ammonia, and other gases, as well as gasoline, oil, petrochemical feedstocks, water, and other liquids.
Flow detectors, such as orifice plates, are widely used to measure the flow rate of the fluid in the pipeline in order to monitor and control the flow rate, efficiency and effectiveness of the process, refinery, or equipment utilizing the pipeline. Orifice plates are usually mounted between orifice flanges and one or more seals or gaskets and installed between similar size pipes. Orifice plates customarily have a constricted opening that is smaller than the adjacent pipes to which they are attached in order to increase the flow and velocity of the fluid as it passes through the orifice plate. By knowing the inside diameter of the orifice hole and the adjacent pipes, and detecting (sensing) the difference in pressure of the fluid entering and exiting the orifice plate, the flow rate of the fluid can be accurately measured.
Over the years a variety of orifice plates, orifice flanges, seals, and gaskets have been suggested. Typifying these prior art orifice plates, orifice flanges, seals, and gaskets, as well as other devices, are those shown in U.S. Pat. Nos. 1,133,320; 1,248,058; 1,648,708; 1,805,236; 1,869,577; 2,148,101; 2,269,486; 2,520,089; 2,979,732; 3,750,710; 3,930,656; 3,983,903; and 4,357,863. These prior art orifice plates, orifice flanges, seals, gaskets, and other devices have met with varying degrees of success.
Many conventional orifice plate assemblies, however, leak during usage. This can present a dangerous situation and hazard in oil refineries, petrochemical plants, and downstream pipelines where a substantial amount of pipes are used to transport large quantities of hot hydrocarbon streams in excess of 500.degree. F. Such leakage can scald and injure operating personnel, create a hazardous spill, pollute the soil and groundwater, create explosive conditions, and cause undesired toxic emissions into the atmosphere.
It is, therefore, desirable to provide an improved orifice plate assembly which overcomes most, if not all, of the above problems.